Various types of sealing, closure or covering members for containers are known and these members are seen to include a number of different material compositions and also function in several different ways. Generally however, the sealing and covering members are known to have a laminated structure and are heat sealed to a top of the container either by conduction or induction heating. The sealing and covering members also may either be included in a cap or alternatively bonded to the container without a cap.
Standard induction seals or coverings have included laminated structures made up of an upper half and a lower half which separate from each other when the container is opened. The seals generally include a compressing agent (pulp board or polyethylene foam) and an induction membrane layer (aluminum foil) with a wax layer between to keep in place during processing. The membrane layer further includes an adhesive layer on its bottom surface which is generally a heat activated adhesive layer. During bottling operations, the seal is placed between the rim of the filled container and the cap. When energy is applied, the induction membrane layer becomes heated, thereby melting the wax and activating the adhesive. The adhesive layer bonds the membrane to the rim and the compressing agent generally remains lodged in the inner portion of the cap. The wax is absorbed into the compressing agent.
Upon opening, the upper and lower halves of the sealing member separate with ease as the wax bond is no longer present leaving the upper half (typically board or paper) in the cap while the lower half remains sealed to the rim of the container. Such a seal is referred to as a two piece seal or liner; as after the cap is removed the liner has separated into two parts. Standard induction seals are also known to both include removal tabs secured to or integral with the lower half of the member and also exclude tabs altogether leaving the lower half as just a seal bonded to the rim of the container.
Standard induction seals are also known to include additional layers and alternative layers of materials in the laminated structure, such as synthetic foam rather than pulp board as well as multi-foam layers in both upper and lower halves of the laminated seal structures. Most typically, expensive raw materials such as 125 micron high density expanded polyethylene foam and 20 micron Aluminum are used in one or more layers of the standard induction seal structures.
Other known sealing and covering members are also laminated structures heat sealed to a rim of a container; however these structures do not make use of a cap as discussed above, and are referred to as one piece seals or liners. These capless one piece sealing and covering members are bonded to the rim of the container and extend beyond the top surface of the rim to envelop the entire rim of the container within the sealing or covering member. These sealing or covering members are also known to extend beyond the entire rim and adhere to or cover a portion of the container within the sealing or covering member. Additionally, a tab integral with and used to peel off the sealing or covering member also extends beyond the rim of the container as well as beyond the perimeter of the sealing or covering member. The tab protrudes from the perimeter of the sealing and covering member and hangs over a portion of the container when the sealing or covering member is affixed in place. These sealing or covering members are known to be affixed to a standard aluminum can and peel off in one piece by pulling the tab extending beyond the sealing or covering member.
Significantly, known sealing or covering members do not include a substrate which omits expensive raw materials, such as polyethylene foam and aluminum, and is contained substantially within the perimeter of a rim of a container being exclusively affixed to a top surface of the rim. Known sealing and covering members also do not include a substrate which peels off in one piece by pulling a tab contained substantially within the perimeter of the substrate and the periphery of the rim of the container.